The present invention relates to a fluid driven down-the-hole drilling machine, i.e. a drilling machine driven by liquid or gas. More specifically the invention relates to a down-the-hole drilling machine provided with a backhammer for freeing a drill bit which has become stuck.
In a prior art backhammer for down-the-hole drilling machines, see DE 3802391, a separate backhammer unit is used which when needed is connected to the drill string in order to free the drill bit by means of impacts in a direction away from the drill bit. This device is very time-consuming to use.